Stress Hormones

Question 1

What are some of the physical and psychological stressors studies in domestic animals?

Answer 1

-Physical stressors
- Cold
- Heat
- Transportation
- Feed deprivation/restriction
- Noise

Psychological stressors
- Weaning
- Social isolation/mixing
- Restraint

Question 2

Effects of stress

Answer 2

Affects homeostasis which alters endocrine milieu. Organism will try to return to homeostasis and will use a large number of hormones to try and do this.

Question 3

Stress and productivity

Answer 3

Widely studied because of the impact stress has on productivity/yield

Question 4

Why is stress bad for domesticated species?

Answer 4

Affects:
o Growth
o Reproduction
o Feeding
o Metabolism
o Immune system
o Body weight
o Behaviour
o Several other physiological parameters

Question 5

Main hormones that mediate stress response

Answer 5

1. Catecholamines
2. Glucocorticoids
3. Mineralocorticoids

Question 6

What hormones are released from zona glomerulosa (adrenal cortex)?

Answer 6

Mineralocorticoids (ex. aldosterone)

Question 7

What hormones are released from zona fasciculata (adrenal cortex)?

Answer 7

Glucocorticoids (ex. cortisol, corticosterone, cortisone)

Question 8

What hormones are released from adrenal medulla?

Answer 8

Stress hormones (ex. epinephrine and norepinephrine)

Question 9

What is the main biomarker for stress in domestic animals?

Answer 9

Cortisol

Measured using immunoassays

Question 10

Stress effects in rainbow trout

Answer 10

• Cortisol levels increases after the introduction of stressor
• Glucose and lactate levels show a corresponding increase

Question 11

Owners and dog stress

Answer 11

• Long-term cortisol levels of human have huge effect on the dogs long-term cortisol levels
• Human neuroticism, openness and conscientiousness will also play a role

Question 12

Stress induced metabolic and non-metabolic changes

Answer 12

Stress can be internal or external

Can cause a short-term or long-term stress response
- Short-term (sympatho-adrenomedulary system): nervous system sends signal to adrenal medulla (gland) which results in the release of the catecholamines.

• Long-term (HPA axis): Brain releases corticotropin-releasing hormone (CRH) which stimulates the corticotrope cells of the anteriorpituitary to release ACTH. ACTH stimulates adrenal cortex to release mineralcorticoids and glucocorticoids

Question 13

Effects caused by the release of catecholamines

Answer 13

• increases heart rate and blood pressure
• liver converts glycogen to glucose and releases glucose to blood
• dilation of bronchioles
• changes in blood flow patterns leading to increases alertness, decreases digestive system activity
• reduced urine output
• increases metabolic rate

Question 14

Effects caused by mineralocorticoids and glucocorticoids

Answer 14

• retention of Na and H2O by kidneys
• increases blood volume and blood pressure
• increase gluconeogenesis
• decreases insulin sensitivity
• decrease in GH and T3
• decreases in immune/inflammatory response
• increase fat and protein mobilization

Question 15

Cortisol and insulin sensitivity

Answer 15

• increase in cortisol results in decrease insulin sensitivity

Question 16

Stress during interdigestive period (eg. Elderly person slips and falls on ice)

Answer 16

• increase cortisol
• decrease insulin/glucagon ratio
• increase in epinephrine and norepinephrine

Question 17

Chronically elevated levels of cortisol in otherwise well-fed person

Answer 17

• increase cortisol
• increase insulin/glucagon
• decreases epinephrine and norepinephrine

Question 18

Hormone regulation from stress during interdigestive period

Answer 18

liver
- increases glycogenolysis and gluconeogenesis

Skeletal muscle
- Increase proteolysis and glycogenolysis
- Decrease protein synthesis and Glut 4 glucose uptake

Adipose tissue
- Increases lipolysis
- Decreases lipogenesis and Glut 4 glucose transport

Question 19

Hormone regulation from chronically elevated levels of cortisol in otherwise well-fed individual

Answer 19

CNS
- Increased appetite

Liver
- Increased hepatic glycogen synthesis

Skeletal muscle
- Increased proteolysis
- Decreased Glut 4

Adipose tissue
- Decrease lipolysis and Glut 4 glucose transport
- Increases triglyceride synthesis and preadipocyte to adipocyte differentiation